Improve torch.utils.tensorboard docs (#19915)
Summary:
This adds method details and corrects example on the page that didn't run properly. I've now confirmed that it runs in colab with nightly.
For those with internal access the rendered result can be seen at https://home.fburl.com/~orionr/pytorch-docs/tensorboard.html
cc lanpa, soumith, ezyang, brianjo
Pull Request resolved: https://github.com/pytorch/pytorch/pull/19915
Differential Revision: D15137430
Pulled By: orionr
fbshipit-source-id: 833368fb90f9d75231b8243b43de594b475b2cb1
